DLLs are advanced clock management circuits employed in systems supporting high bandwidth transfer rates. DLLs allow for precise synchronization of external and internal clocks. More particularly, DLLs generate internal clocks with a known phase relationship to an external input clock.
Low Voltage Differential Signaling (LVDS) receivers and transmitters often employ DLLs to generate multiple internal clocks having phases with a known relationship to the external input clock. A DLL typically consists of a chain of variable delay elements. When properly adjusted, the sum of all the delays in the delay elements equals the external clock's period. When this occurs, the DLL is said to be locked to the external clock. In some circumstances, however, the DLL locks to a multiple of the clock period (e.g., two or three times the clock period) resulting in erroneous operation.
Accordingly, a need remains for an improved DLL harmonic detector and associated method.